Optical elements have been proposed that are capable of switching optical states.
Japanese Laid-open Patent Publication No. 2012-181389 discloses a so-called electrodeposition element. The electrodeposition element mainly includes a pair of transparent electrodes arranged opposite each other and an electrolyte layer held between the pair of transparent electrodes, the electrolyte layer containing an electrodeposition material including silver. The electrodeposition element typically has a planar size of about 10 mm2.
The electrolyte layer is substantially transparent, and the electrodeposition element is in transparent state at steady state (while no voltage is applied). When a voltage is applied between the pair of transparent electrodes, an electrochemical reaction (an oxidation-reduction reaction) occurs which causes the electrodeposition material (silver) in the electrolyte layer to be precipitated and deposited on one of the electrodes. The electrodeposition material, when precipitated and deposited on a surface of one of the electrodes that is comparatively planar, forms a mirror surface, and the electrodeposition element is brought into a mirror surface (high light reflecting) state.
Japanese Laid-open Patent Publication No. 2007-134143 discloses a so-called electrochemical luminescent element. The electrochemical luminescent element includes a pair of substrates, a pair of transparent electrodes, and a layer held between the pair of transparent electrodes and including an electrochemical luminescent material. Upon application of voltage, excitation and deactivation of the cation radical and anion radical occur, which results in emission of light.
Japanese Laid-open Patent Publication No. 2004-170613 discloses a so-called electrochromic element. The electrochromic element includes a pair of substrates, a pair of transparent electrodes, and a layer held between the pair of transparent electrodes and including an electrochromic material. Upon application of voltage, due to an electrochemical reaction, the electrochromic material changes its molecular structure, causing discoloration.